• Title/Summary/Keyword: Advance Chamber

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An Experimental Study on Air Evacuation from Lunar Soil Mass and Lunar Dust Behavior for Lunar Surface Environment Simulation (달 지상환경 모사를 위한 지반 진공화 및 달먼지 거동에 대한 실험적 연구)

  • Chung, Taeil;Ahn, Hosang;Yoo, Yongho;Shin, Hyu-Soung
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.39 no.2
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    • pp.327-333
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    • 2019
  • For sustainable lunar exploration, the most required resources should be procured on site because it takes tremendous cost to transfer the resources from the Earth to the Moon. The technologies required for use of lunar resources refers to In-Situ Resource Utilization (ISRU). As the ISRU technology cannot be verified in the Earth, a lunar surface environment simulator is necessary to be prepared in advance. The Moon has no atmosphere, and the average temperature of the lunar surface reaches to $107^{\circ}C$ during the daytime and $-153^{\circ}C$ at night. The lunar surface is also covered with very fine soils with sharp particles that are electrostatically charged by solar radiation and solar wind. In this research, generation of vacuum environment with lunar soil mass in a chamber and simulation of electrostatically charged soils are taken into consideration. It was successful to make a vacuum environment of a chamber including lunar soils without soil disturbance by controlling evacuation rate of a vacuum chamber. And an experiment procedure for simulating the charged lunar soil was suggested by theoretical consideration in charging phenomena on lunar dust.

Recent Advance in High Pressure Induction Plasma Source

  • Sakuta, T.
    • Journal of the Korean institute of surface engineering
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    • v.34 no.5
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    • pp.395-402
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    • 2001
  • An induction thermal plasma system have been newly designed for advanced operation with a pulse modulated mode to control the plasma power in time domain and to create non-equilibrium effects such as fast quenching of the plasma to produce new functional materials in high rate. The system consists of MOSFET power supply with a maximum power of 50 kW with a frequency of 460 kHz, an induction plasma torch with a 10-turns coil of 80 mm diameter and 150 mm length and a vacuum chamber. The pulse modulated plasma was successfully generated at a plasma power of 30 kW and a high pressure of 100 kPa, with taking the on and off time as 10 ms, respectively. Measurements were carried out on the time-dependent spectral lines emitted from Ar species. The dynamic behavior of plasma temperature in a pulse cycle was estimated by the Boltzmann plot and the excitation temperature of Ar atom was found to be changed periodically from around 0.5 to 1.7 eV during the cycle. Two application regions of the induction thermal plasma newly generated were introduced to material processing with high rate synthesis based on non equilibrium effects, and to the finding of new arc quenching gases coming necessary for power circuit breaker, which is friendly with earth circumstance alternative to SF6 gas.

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Study on Stable Fly Eradication by Sterile-Male Technigue (3) Mass Rearing of the Stable Fly, Stomoxys calcitrans L. (웅성불임기술을 이용한 쇠파리 구제에 관한 연구 (3) 쇠파리의 인공대량사육에 관하여)

  • Chung K. H.;Ryu J.;Kwon S. H.
    • Korean journal of applied entomology
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    • v.13 no.3 s.20
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    • pp.141-144
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    • 1974
  • The vinyl-shielded rearing chamber was controlled by automatic electric heater to maintain relatively constant temperature and under this condition, it took 13 to 14 days from egg to adult and 8 days for their preoviposition. The pupal weight was not varied with the advance of generation, whereas was greatly effected by temperature changes. Since only $60\%$ of the pupae was able to classify the sex by pupal weight, a mechanical device will be needed for the further sexing.

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Ascophyllum and Its Symbionts. VIII. Interactions Among Ascophyllum nodosum (Phaeophyceae), Mycophycias ascophylli (Ascomycetes) and Elachista fucicola (Phaeophyceae)

  • Deckert, Ronald J.;Garbary, David J.
    • ALGAE
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    • v.20 no.4
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    • pp.363-368
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    • 2005
  • The brown alga Ascophyllum nodosum and its mutualistic, ascomycete symbiont, Mycophycias ascophylli, form a complex ‘rganism’or symbiotum. Here we show the interaction of the symbiotum to the abundant brown algal epiphyte, Elachista fucicola. Microscopy of field-collected plants shows morphological responses of A. nodosum to the common epiphyte E. fucicola. When E. fucicola attaches to A. nodosum a bundle of several to dozens of rhizoids penetrates into the host. On the surface of the host, the cells proliferate to form a donut-shaped ring, 100-200 μm in height that surrounds the thallus of E. fucicola. A pit forms in advance of the rhizoids and the cells of A. nodosum break down. This leaves the network of fungal hyphae partially intact and intermingling with the epiphyte rhizoids and its lowermost cells. After the pit is formed, the cells of A. nodosum bordering the infection chamber redifferentiate an epidermal layer. Neither the host nor its mutualistic fungus, M. ascophylli appears to recognize E. fucicola as an invader and to prevent the attachment and growth of this epiphyte. Based on the physical damage to the host caused by invading rhizoids, we conclude that the relationship of E. fucicola to A. nodosum is that of a parasite and its host.

Fuel Stratification Effects of LPG-DME Compression Ignition Engine (LPG-DME 압축착화 엔진의 성층화 영향)

  • Yeom, Ki-Tae;Bae, Choong-Sik
    • Transactions of the Korean Society of Automotive Engineers
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    • v.16 no.1
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    • pp.78-85
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    • 2008
  • The exhaust emission characteristics of a liquefied petroleum gas-di-methyl ether (LPG-DME) compression ignition engine was investigated under homogeneous charge, stratified charge and diffusion combustion conditions. LPG was used as the main fuel and injected into the combustion chamber directly. DME was used as an ignition promoter and injected into the intake port. Different LPG injection timings were tested to verify the combustion characteristics of the LPG-DME compression ignition engine. The combustion was divided into three region which are homogeneous charge, stratified charge, and diffusion combustion region according to the injection timing of LPG. The HC emission was reduced with LPG stratification. However, the carbon monoxide and particulate matter emissions were increased. The ignition timing was advanced with LPG stratification. This advance combustion was because of charge temperature and cetane number stratification with LPG.

Review of the KCAB International Arbitration Rules, Recently Revised, in Comparison with the Revised ICC Arbitration Rules (대한상사중재원 국제중재규칙의 개정 동향 - ICC 중재규칙의 개정과 비교하여 -)

  • Park, Won-Hyung
    • Journal of Arbitration Studies
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    • v.22 no.2
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    • pp.159-176
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    • 2012
  • The Korean Commercial Arbitration Board (KCAB) recently revised its International Arbitration Rules in a way that reflects its efforts to advance its procedures, leading directly to improved competitiveness as an arbitration institute. Apart from certain limitations, the KCAB's international arbitration rule revision introduced several new arbitration mechanisms, including fast-track arbitration and an empowered administrative office. The International Chamber of Commerce (ICC) released a revised set of arbitration rules (ICC Arbitration Rules), which have been said to be probably the most consulted-on arbitration rules ever. Even though the changes codify existing ICC court practice and add to the 1998 rules only provisions felt necessary in light of input from the users of arbitration, some of the changes will have huge implications for future aspects of arbitration mechanisms, especially those of KCAB. Although it remains to be seen what impact the ICC Arbitration Rules will have in practice, the new rules have been well received by the arbitration community and represent a modern set of provisions consistent with the current needs of the users of international arbitration. That is why, here in the Korean arbitration environment, further research is needed on the possibilities of introducing several elements of the revised ICC Arbitration Rules to improve the speed and cost efficiency of international arbitration.

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An Archaeological Review of the Inscribed Bricks Excavated from the Tomb of Jang Mui: A Focus on the Collection of the National Museum of Korea (장무이묘 출토 명문전(銘文塼)의 고고학적 검토 -국립중앙박물관 소장품을 중심으로)

  • Lee Nakyung
    • Bangmulgwan gwa yeongu (The National Museum of Korea Journal)
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    • v.1
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    • pp.36-73
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    • 2024
  • The Tomb of Jang Mui located in Bongsan-gun, Hwanghae-do Province has attracted much attention since its first investigation due to the inscribed bricks found there that have allowed the guessing of the name and official title of its occupant and construction date. Inscriptions on these bricks, such as the "Prefect of Daebang Commandery Jang Mui" and the "Mu" (戊, the fifth sign of the Chinese calendar), and "Sin" (申, the ninth sign of the Chinese zodiac), have become the basis for believing the location of the government office of Daebang Commandery to be in Bongsangun, Hwanghae-do Province rather than somewhere in the Hangang River region. From the early days of its investigation, the tomb was suggested as historic remains of the Daebang Commandery along with the Earthen Fortress in Jitap-ri. Inscribed bricks excavated from the Tomb of Jang Mui were featured in several books and articles in the form of photographs and rubbings, leading to a vast body of studies on its construction period and the characteristics of its occupant that drew upon interpretations of the inscriptions. However, the inscribed bricks themselves were not publicly available outside those held in the collection of the University of Tokyo, making it difficult to expect consistent research findings on the types of inscribed bricks and their contents. Following previous studies re-examining the structure of the tomb and the materials used for its construction, most scholars dated the Tomb of Jang Mui to 348, a period after the collapse of Daebang Commandery. However, there is still a lack of adequate examination of the bricks, which account for the majority of the artifacts excavated from the tomb. Among the bricks excavated from most brick chamber tombs, including the Tomb of Jang Mui, only those with inscriptions or designs have been collected. Moreover, among these, only those with inscriptions or designs on the stretcher faces have been documented. Accordingly, the bricks themselves have been notably understudied. This paper intends to reorganize the contents of the inscriptions on eleven types (out of sixty-one pieces) of bricks in the collection of the National Museum of Korea, which make up the majority of the bricks excavated from the Tomb of Jang Mui. It also classified them according to their shapes. Furthermore, it examined the bricks from the Tomb of Jang Mui as architectural materials by focusing on their production techniques, including their forming, drying, and firing. Taking a more specific approach, it then compared the results to other bricks from the second century through the fourth century: those from the brick chamber tombs of the Nangnang and Daebang Commanderies and those from the brick chamber tombs built after Nangnang and Daebang Commanderies were ousted. The examination of bricks from the Tomb of Jang Mui has revealed that these bricks were basically produced using the brick manufacturing techniques of Nangnang, but they incorporated new elements found in bricks from brick chamber tombs or brick-and-stone chamber tombs constructed around the mid-fourth century in terms of their size, the use of lime, and the number of inscribed bricks. This supports the prevailing view that the date of the construction of the Tomb of Jang Mui is 348. The Tomb of Jang Mui sustained the existing brick chamber tomb burial tradition, but its ceiling was finished with stone. It demonstrates a blending of the brick chamber tomb practice of the Nangnang and Daebang Commanderies by using bricks produced based on related techniques, but with new elements such as the addition of a lime layer to the bricks. This fusion reflects the political circumstances of its time, such as the expulsion of the Daebang Commandery and the advance of the Goguryeo Kingdom, leading to diverse interpretations. Given archaeological evidence such as the structure, materials, and location of the tomb, the Tomb of Jang Mui appears to be highly related to the Goguryeo Kingdom. However, the forms of the inscribed bricks and the contents of the inscriptions share similarities with brick chamber tombs constructed during the third and fourth centuries in the Jiangsu and Zhejiang regions in China. Further studies on whether the use of lime was an influence from Goguryeo or a continuation of the Daebang tradition and a comparative examination with contemporaneous stone ceiling tombs will provide a more refined understanding of the Tomb of Jang Mui.

Numerical Analysis of EPB TBM Driving using Coupled DEM-FDM Part I : Modeling (개별요소법과 유한차분법 연계 해석을 이용한 EPB TBM 굴진해석 Part I : 모델링)

  • Choi, Soon-wook;Lee, Hyobum;Choi, Hangseok;Chang, Soo-Ho;Kang, Tae-Ho;Lee, Chulho
    • Tunnel and Underground Space
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    • v.30 no.5
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    • pp.484-495
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    • 2020
  • To numerically simulate the advance of EPB TBM, various type of numerical analysis methods have been adopted including discrete element method (DEM), finite element method (FEM), and finite difference method (FDM). In this paper, an EPB TBM driving model was proposed by using coupled DEM-FDM. In the numerical model, DEM was applied in the TBM excavation area, and contact properties of particles were calibrated by a series of triaxial tests. Since the ground around the excavation area was coupled with FDM, the horizontal stress considering the coefficient of earth pressure at rest could be applied. Also, the number of required particles was reduced and the efficiency of the analysis was increased. The proposed model can control the advance rate and rotational speed of the cutter head and screw conveyor, and derive the torque, thrust force, chamber pressure, and discharging during TBM tunnelling.

Analysis of correlation between shield TBM construction field data and settlement measurement data (쉴드 TBM 시공데이터와 지반침하 계측데이터 간 상관성 분석)

  • Jung, Ye-Rim;Nam, Kyoung-Min;Kim, Han-Eol;Ha, Sang-Gui;Yun, Ji-Seok;Cho, Jae-Eun;Yoo, Han-Kyu
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.24 no.1
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    • pp.79-94
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    • 2022
  • The demand for tunnel construction is increasing as part of underground space development due to urban saturation. The shield TBM method minimizes vibration and noise and minimizes ground deformation that occurs simultaneously with excavation, and shield TBM is generally applied to tunnel construction in urban areas. The importance of urban ground settlement prediction is increasing day by day, and in the case of shield TBM construction, ground deformation is minimized, but ground settlement due to tunnel excavation inevitably occurs. Therefore, in this study, the correlation between shield TBM, which is highly applicable to urban areas, and ground settlement is analyzed to suggest the shield TBM construction factors that have a major effect on ground settlement. Correlation analysis was performed between the shield TBM construction data and ground settlement measurement data collected at the actual site, and the degree of correlation was expressed as a correlation coefficient "r". As a result, the main construction factors of shield TBM affecting ground settlement were thrust force, torque, chamber pressure, backfill pressure and muck discharge. Based on the results of this study, it is expected to contribute to the presentation of judgment criteria for major construction data so that the ground settlement can be predicted and controlled in advance when operating the shield TBM in the future.

A Study on Engine Durability Considering Oil Consumption and Wear of Piston-Ring Pack and Cylinder Bore (피스톤 링 팩 및 실린더 보아 마모와 오일소모를 고려한 엔진 내구수명 연구)

  • Chun Sang-Myung
    • Tribology and Lubricants
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    • v.22 no.3
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    • pp.155-163
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    • 2006
  • Ring, groove and cylinder bore wear may not be a problem in most current automotive engines. However, a small change in ring face, groove geometry and cylinder bore diameter can significantly affect the lubrication characteristics and ring axial motion. This in turn can cause to change inter-ring pressure, blowby and oil consumption in an engine. Therefore, by predicting the wear of piston ring face, ring groove and cylinder bore altogether, the changed ring end gap and the changed volume of gas reservoir can be calculated. Then the excessive oil consumption can be predicted. Being based on the calculation of gas flow amount by the theory of piston ring dynamics and gas flow, and the calculation of oil film thickness and friction force by the analysis of piston ring lubrication, the calculation theory of oil amount through top ring gap into combustion chamber will be set. This is estimated as engine oil consumption. Furthermore, the wear theories of ring, groove and cylinder bore are included. Then the each amount of wear is to be obtained. The changed oil consumption caused by the new end gap and the new volume of oil reservoir around second land, can be calculated at some engine running interval. Meanwhile, the wear amount and oil consumption occurred during engine durability cycle are compared with the calculated values. Next, the calculated amount of oil consumption and wear are compared with the guideline of each part's wear and oil consumption. So, the timing of part repair and engine life cycle can be predicted in advance without performing engine durability test. The wear data of rings, grooves and cylinder bore are obtained from three engines before and after engine durability test. The calculated wear data of each part are turn out to be around the band of averaged test values or a little below.